| Company Name | Company Location | Company Type | Most Recent Production | |
|---|---|---|---|---|
| 1 | Ody Oil Corp. | Oil & Gas Operator | Oct 1994 | |
| 2 | Oil & Gas Property MGMT., Inc. | Dallas, TX 75201 | Oil & Gas Operator | Jul 1996 |
| 3 | Oleum Incorporated | Oil & Gas Operator | Mar 1996 | |
| 4 | Oleum Operating Company, L.C. | Longview, TX 75606 | Oil & Gas Operator | Dec 2021 |
| 5 | Oleum Operating La LLC | Oil & Gas Operator | Nov 2022 | |
| 6 | Opmi Operating Company | Houston, TX 77057 | Oil & Gas Operator | Jun 2008 |
| 7 | Oracle Oil, LLC | Oil & Gas Operator | Jul 2013 | |
| 8 | Oryx Energy Company | Dallas, TX 75221 | Oil & Gas Operator | May 2002 |
| 9 | Oxy Petroleum Inc | Oil & Gas Operator | Jan 1986 | |
| 10 | Oxy USA Inc | Houston, TX 77046 | Oil & Gas Operator | Oct 2025 |